1. Field of the Invention
The present invention relates to an image processing system which comprises a plurality of processors.
2. Description of the Prior Art
Heretofore, there has been known an image processing system comprising a plurality of processors as disclosed in UK Patent Application GB2213621A, for example. The conventional image processing system has suffered various drawbacks. When a large amount of data to be processed is supplied from a host computer to a processing unit composed of processors, the interpretation speed of the processing unit is so slow that the host computer is required to repeat the transmission of the same data or transmit data slowly over a long period of time, resulting in a timing-consuming data communication process.
After the host computer has transmitted data to the processing unit, the host computer is unable to recognize the transmitted data again. Though the host computer can recognize the transmitted data if it is stored in the host computer, the host computer is no longer able to recognize the stored data when it has any trouble which has modified the stored data.
In the image processing system, a processing program supplied from the host computer is delivered to the processors by a system control processor, and the processors process any input data signals according to the supplied program. Since the system control processor needs to be energized first immediately after the image processing system is switched on, the system control processor has a ROM as a program memory. If the processing program is complex and requires a lot of signal processing, then the system control processor necessarily has a large circuit scale as it requires a large-capacity ROM or a number of ROMs. A RAM may be used as a program memory and a processing program to be used by the system control processor may be loaded from the host computer into the RAM. However, the time to transfer the processing program from the host computer to the RAM is long, and hence the time consumed to process necessary input data is also long.
The image processing system with plural processors process input signals according to distributed or parallel processing. It is therefore difficult to locate a program bug based on the processed data. In the distributed image processing system, the processing program is divided into a plurality of programs which are supplied to the respective processors. The processors then process input signals according to the divided programs supplied respectively thereto. In the distributed processing, the processors process input signals in different manners, or the processors are divided into a plurality of groups which process input signals differently. In the parallel processing, the processors process different data according to the same signal processing sequence.
In the distributed or parallel image processing system, one job is divided into smaller jobs which are simultaneously processed by the respective processors, and the results of signal processing by the processors are combined into a final output signal. In the event of a program bug, therefore, it is difficult to find which smaller job is suffering the bug. As a consequence, a large-scale program cannot be developed with high efficiency.